fixing init_chain script to not clobber new params (#1139)

dockernet/src/init_chain.sh

@@ -362,7 +362,7 @@ for (( i=2; i <= $NUM_NODES; i++ )); do
  genesis_json="${STATE}/${node_name}/config/genesis.json"
 
  # add the main node as a persistent peer
- sed -i -E "s|persistent_peers = .*|persistent_peers = \"${MAIN_NODE_ID}\"|g" $config_toml
+ sed -i -E "s|^persistent_peers = .*|persistent_peers = \"${MAIN_NODE_ID}\"|g" $config_toml
  # copy the main node's genesis to the peer nodes to ensure they all have the same genesis
  cp $MAIN_GENESIS $genesis_json
 
@@ -371,4 +371,4 @@ done
 
 # Cleanup from seds
 rm -rf ${MAIN_CONFIG}-E
-rm -rf ${MAIN_GENESIS}-E
+rm -rf ${MAIN_GENESIS}-E